Caffeine is an inhibitor of phosphodiesterase. therefore, the cells of a person who has recently consumed coffee would have increased levels of
a) phosphorylated proteins
b) camp
c) adenylyl cyclase
d) activated g proteins

B) cAMP

Explanation:

Phosphodiesterase is an enzyme that breaks a phosphodiester bond, for example in molecules such as cAMP and cGMP. So, phosphodiestarases are  are regulators of signal transduction: regulate the duration of signaling pathway.

Caffeine is  central-nervous-system stimulant and the mechanisms of its action usually are: mobilization of intracellular calcium or inhibition of specific phosphodiesterases.

the answer is c.) there is a warm front in region a and a stationary front in region b.